There are numerous examples where specific hidden positions within items, animals or humans need to be determined with accuracy. For example, It is generally acknowledged by oncologists that directing a source of radiation accurately at an internal tumor (e.g. carcinoma) for treatment is difficult because the precise location of the tumor is elusive. As a result, substantial amounts of radiation frequently miss the intended target, i.e. the tumor or unwanted cellular growth. This leads to the danger of radiating healthy body tissue, giving rise to tissue damage and extensive bleeding, at times from vital organs in the vicinity of the tumor.
Under the best of circumstances, preparation for radiation treatment includes obtaining tomographic images of the tumor and surrounding tissue, typically recorded several days prior to the onset of radiation treatment. The 3-D reconstruction of the images results in accurately locating the tumor in relation to the body as a whole. However, since radiation treatment may occur over a matter of months, there can be considerable shifts or displacements of the organ-containing tumor from the position originally determined from the tomograph. As a result, relying on the original tomographic positioning data can result in the radiation beam missing the target (tumor or other internal structure) either partially or even completely, striking instead regions not meant to be irradiated.